In-vehicle reporting apparatus and reporting system

ABSTRACT

Provided are an in-vehicle reporting apparatus and a reporting system configured to prevent errors in reporting. The in-vehicle reporting apparatus stores a mounting position of each tire in association with identification information identifying the tire, a vehicle height acquisition unit acquires a vehicle height of the vehicle, a vehicle height determination unit determines whether the vehicle height is greater than or equal to a predetermined height, and a reporting unit reports information that depends on the mounting position of a tire stored in the storage unit in association with acquired identification information and on acquired air pressure information of the tire when the acquired vehicle height is not greater than or equal to the predetermined height, and does not report information that depends on the mounting position of the tire, when the acquired vehicle height is greater than or equal to the predetermined height.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national stage of PCT/JP2015/084102 filedDec. 4, 2015, which claims priority of Japanese Patent Application No.JP 2014-247117 filed Dec. 5, 2014.

TECHNICAL FIELD

The instant invention relates to an in-vehicle reporting apparatus forperforming reporting that depends on air pressure information related torespective air pressures of a plurality of tires provided on a vehicle,and a reporting system that includes the reporting apparatus.

BACKGROUND

In recent years, TPMSs (Tire Pressure Monitoring Systems) that detectthe air pressures of a plurality of tires provided on a vehicle and emita warning or the like to a user in the case where the detected airpressure is abnormal have been available. For example, a TPMS includes atransmission apparatus that detects the air pressure of a tire andwirelessly transmits the detected air pressure, and an in-vehiclereporting apparatus that receives the air pressure wirelesslytransmitted from the transmission apparatus and performs reporting thatdepends on the received air pressure. Generally, the transmissionapparatus is disposed on a tire wheel provided on the vehicle anddetects the air pressure of a tire mounted on the tire wheel. Thein-vehicle reporting apparatus, for example, reports the received airpressure to the user as the air pressure of the tire from which the airpressure was detected.

A TPMS (tire pressure monitoring apparatus) described in JP 2006-159961Aincludes means for registering a tire identification code thatidentifies each of a plurality of tires that are provided on a vehiclein a memory, and means for judging that a tire has been replaced. ThisTPMS updates the tire identification code registered in the memory inthe case where it is judged that a tire has been replaced. Accordingly,the TPMS described in JP 2006-159961A is able to prevent errors in thecorrespondence relationship of received air pressures and tires, even inthe case where the position of a tire with respect to the vehiclechanges as a result of tire rotation or the like, for example, byupdating the tire identification code. Thus, the TPMS described in JP2006-159961A is able to report the air pressure without mistaking thetire from which the air pressure was detected.

However, with the TPMS described in JP 2006-159961A, a specialconfiguration such as a contact switch or an infrared switch provided onthe axle needs to be used, in order for the means for judging that atire has been replaced to judge whether the tire wheel is attached tothe vehicle. Thus, with the TPMS of JP 2006-159961A, there is a problemin that costs concerning the configuration of the system increase, dueto needing to provide the special configuration. Also, the air pressuremonitoring apparatus needs to receive a signal that is transmitteddepending on the operating state of a centrifugal force sensor providedin the transmission apparatus (tire pressure sensor). Thus, with theTPMS of JP 2006-159961A, in the case where the air pressure monitoringapparatus is not able to receive this signal, the judging means is notable to judge that the tire has been replaced, and there is a risk ofperforming erroneous reporting, due to the correspondence relationshipof the received air pressure and the tire from which the air pressurewas detected being in error.

An object of the instant invention is to provide an in-vehicle reportingapparatus and a reporting system that are able to prevent errors inreporting that depends on acquired air pressure information, when airpressure information related to respective air pressures of a pluralityof tires provided on a vehicle is acquired, and to suppress an increasein costs concerning the configuration.

SUMMARY OF THE INVENTION

An in-vehicle reporting apparatus according to one aspect of the presentinvention is an in-vehicle reporting apparatus that has an air pressureinformation acquisition unit configured to acquire identificationinformation identifying each of a plurality of tires provided on avehicle and air pressure information related to an air pressure of eachof the plurality of tires, and that performs reporting that depends onthe identification information and the air pressure information acquiredby the air pressure information acquisition unit, the apparatusincluding a storage unit configured to store a mounting position of eachof the plurality of tires in association with the identificationinformation identifying the tire, a vehicle height acquisition unitconfigured to acquire a vehicle height of the vehicle, a vehicle heightdetermination unit configured to determine whether the vehicle heightacquired by the vehicle height acquisition unit is greater than or equalto a predetermined height, and a detection unit configured to reportinformation that depends on the mounting position of a tire stored inthe storage unit in association with the identification informationacquired by the air pressure information acquisition unit and on the airpressure information of the tire acquired by the air pressureinformation acquisition unit, in a case where the vehicle heightdetermination unit determines that the acquired vehicle height is notgreater than or equal to the predetermined height, and to not report atleast information that depends on the mounting position of the tire, ina case where the vehicle height determination unit determines that theacquired vehicle height is greater than or equal to the predeterminedheight.

A reporting system according to one aspect of the present inventionincludes the above-mentioned in-vehicle reporting apparatus and aplurality of transmission apparatuses respectively disposed on aplurality of tire wheels provided on a vehicle and configured to detectan air pressure of a corresponding tire and transmit air pressureinformation including the detected air pressure and identificationinformation identifying the corresponding tire, the air pressureinformation acquisition unit being configured to acquire the airpressure information and the identification information transmitted fromeach of the plurality of transmission apparatuses.

Note that the instant invention can be not only realized as anin-vehicle reporting apparatus and a reporting system that are providedwith such characteristic processing units, but can also be realized as areporting method in which the characteristic processing is configured assteps, or as a program for causing a computer to execute the steps.Also, the instant invention can be realized as a semiconductorintegrated circuit that realizes part or all of the in-vehicle reportingapparatus and the reporting system, or as another system that includesthe in-vehicle reporting apparatus and the reporting system.

According to the above, errors in reporting that depends on acquired airpressure information can be prevented when air pressure informationrelated to respective air pressures of a plurality of tires provided ona vehicle is acquired, and an increase in costs concerning theconfiguration can be suppressed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram showing an exemplary configuration of areporting system in an embodiment.

FIG. 2 is a block diagram showing the configuration of a transmissionapparatus.

FIG. 3 is a block diagram showing the configuration of an in-vehiclereporting apparatus.

FIG. 4 is an illustrative diagram showing a specific example of acorrespondence table.

FIG. 5A is a diagram showing a specific example of a reporting mode of areporting unit.

FIG. 5B is a diagram showing a specific example of the reporting mode ofthe reporting unit.

FIG. 6 is a flowchart showing a processing procedure performed by thein-vehicle reporting apparatus when determining whether a tire has beenreplaced based on the vehicle height of a vehicle.

FIG. 7 is a flowchart showing a processing procedure performed by thein-vehicle reporting apparatus when reporting information related to theair pressure of a tire.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Initially embodiments of the present invention will be recited. Also,the embodiments described below may be suitably combined at least inpart.

(1) An in-vehicle reporting apparatus according to one aspect of thepresent invention is an in-vehicle reporting apparatus that has an airpressure information acquisition unit configured to acquireidentification information identifying each of a plurality of tiresprovided on a vehicle and air pressure information related to an airpressure of each of the plurality of tires, and that performs reportingthat depends on the identification information and the air pressureinformation acquired by the air pressure information acquisition unit,the apparatus including a storage unit configured to store a mountingposition of each of the plurality of tires in association with theidentification information identifying the tire, a vehicle heightacquisition unit configured to acquire a vehicle height of the vehicle,a vehicle height determination unit configured to determine whether thevehicle height acquired by the vehicle height acquisition unit isgreater than or equal to a predetermined height, and a detection unitconfigured to report information that depends on the mounting positionof a tire stored in the storage unit in association with theidentification information acquired by the air pressure informationacquisition unit and on the air pressure information of the tireacquired by the air pressure information acquisition unit, in a casewhere the vehicle height determination unit determines that the acquiredvehicle height is not greater than or equal to the predetermined height,and to not report at least information that depends on the mountingposition of the tire, in a case where the vehicle height determinationunit determines that the acquired vehicle height is greater than orequal to the predetermined height.

In the instant invention, the storage unit stores the mounting positionsof a plurality of tires in association with identification informationthat identifies the respective tires. The vehicle height acquisitionunit acquires the height of the vehicle. The vehicle heightdetermination unit determines whether the vehicle height acquired by thevehicle height acquisition unit is greater than or equal to apredetermined height. The reporting unit reports information thatdepends on the mounting position of a tire stored in the storage unit inassociation with the acquired identification information and on theacquired air pressure information of the tire, in the case where thevehicle height determination unit determines that the acquired vehicleheight is not greater than or equal to the predetermined height.Accordingly, the in-vehicle reporting apparatus is able to determinewhether a tire has been replaced based on the acquired vehicle height,and to change the reporting mode depending on whether any of theplurality of tires provided on the vehicle have been replaced. Thein-vehicle reporting apparatus is able to report information thatdepends on the mounting position of a tire and the air pressure of thetire in the case where none of the tires have been replaced, and toprevent errors in reporting by, for example, not performing reportingfor every mounting position, in the case where any of the tires havebeen replaced. Also, the in-vehicle reporting apparatus is able to use aconfiguration capable of detecting vehicle height that can be installedin a typical vehicle such as a vehicle height sensor that is used incontrol related to optical axis adjustment of headlights, pressurecontrol of air suspension or the like, and to suppress an increase incosts concerning the configuration.

(2) A configuration is preferably adopted in which the reporting unit isconfigured to report information that depends on the air pressureinformation of the tire acquired by the air pressure informationacquisition unit, in the case where the vehicle height determinationunit determines that the acquired vehicle height is greater than orequal to the predetermined height.

In the instant invention, the reporting unit reports information thatdepends on the air pressure information of the tire acquired by the airpressure information acquisition unit, in the case where the vehicleheight determination unit determines that the acquired vehicle height isgreater than or equal to the predetermined height. Accordingly, thein-vehicle reporting apparatus is able to report information thatdepends on the acquired air pressure without performing reporting forevery mounting position, even in the case where any of the tires havebeen replaced, thus improving convenience.

(3) A configuration is preferably adopted in which the in-vehiclereporting apparatus further includes an air pressure thresholddetermination unit configured to determine whether an air pressureindicated by the acquired air pressure information is less than or equalto a predetermined threshold, and the reporting unit is configured toreport a result of the determination by the air pressure thresholddetermination unit, in the case where the vehicle height determinationunit determines that the acquired vehicle height is greater than orequal to the predetermined height.

In the instant invention, the air pressure threshold determination unitdetermines whether the air pressure that is indicated by the acquiredair pressure information is less than or equal to a predeterminedthreshold. The reporting unit reports the determination result of theair pressure threshold determination unit, in the case where the vehicleheight determination unit determines that the acquired vehicle height isgreater than or equal to predetermined height. Accordingly, thein-vehicle reporting apparatus is able to prevent errors in reporting inthe case where any of the plurality of tires have been replaced, by notreporting, for every mounting position of a tire, information thatdepends on the air pressure of the tire, for example. Also, the user canat least be made aware that the air pressure of one or more of the tiresis low even in the case where a tire has been replaced. Thus,convenience for the user can be improved.

(4) A configuration is preferably adopted in which the vehicle heightacquisition unit is configured to acquire the vehicle height of thevehicle repetitively, and the vehicle height determination unit isconfigured to determine whether the vehicle height repetitively acquiredby the vehicle height acquisition unit is continuously greater than orequal to the predetermined height for greater than or equal to apredetermined time period or a predetermined number of times.

In the instant invention, the vehicle height acquisition unitrepetitively acquires the vehicle height of the vehicle. The vehicleheight determination unit determines whether the vehicle heightrepetitively acquired by the vehicle height acquisition unit iscontinuously greater than or equal to a predetermined height for greaterthan or equal to a predetermined time period or a predetermined numberof times. Accordingly, the in-vehicle reporting apparatus is able tomore accurately determine whether tire replacement has been performed,by determining that tire replacement has been performed in the casewhere the height of the vehicle is continuously greater than or equal tothe predetermined height.

(5) A reporting system according to one aspect of the instant inventionincludes the above-mentioned in-vehicle reporting apparatus and aplurality of transmission apparatuses respectively disposed on aplurality of tire wheels provided on a vehicle and configured to detectan air pressure of a corresponding tire and transmit air pressureinformation including the detected air pressure and identificationinformation identifying the corresponding tire, the air pressureinformation acquisition unit being configured to acquire the airpressure information and the identification information transmitted fromeach of the plurality of transmission apparatuses.

In the instant invention, a plurality of transmission apparatuses arerespectively provided on a plurality of tires provided on a vehicle, anddetect the air pressures of the tires on which they are provided. Also,the plurality of transmission apparatuses transmit air pressureinformation including the detected air pressures and identificationinformation identifying the tires. The above-mentioned in-vehiclereporting apparatus acquires the air pressure information and theidentification information respectively transmitted from the pluralityof transmission apparatuses. Accordingly, the in-vehicle reportingapparatus is able to change the reporting mode depending on whether anyof the plurality of tires provided on the vehicle have been replaced.The in-vehicle reporting apparatus is able to report information thatdepends on the mounting position of a tire and the air pressure of thetire, in the case where none of the tires have been replaced, and toprevent errors in reporting by, for example, not performing reportingfor every mounting position, in the case where any of the tires havebeen replaced. Also, the in-vehicle reporting apparatus is able to use aconfiguration capable of detecting vehicle height that can be installedin a typical vehicle such as a vehicle height sensor that is used incontrol related to optical axis adjustment of headlights, pressurecontrol of air suspension or the like, and to suppress an increase incosts concerning the configuration.

DETAILED DESCRIPTION OF EMBODIMENTS

Specific examples of an in-vehicle reporting apparatus and a reportingsystem according to the embodiments of the present invention will now bedescribed, with reference to the drawings. Note that the presentinvention is not limited to these illustrative examples and is definedby the claims, and all changes which come within the meaning and rangeof equivalency of the claims are intended to be embraced therein.

FIG. 1 is a schematic diagram showing an exemplary configuration of areporting system of the present embodiment. The reporting systemincludes an in-vehicle reporting apparatus 1 provided in a vehicle C,and a transmission apparatus 2 attached to each tire wheel on which ismounted a tire 3 provided on the vehicle C. In the reporting system ofthe present embodiment, the air pressure of each tire 3 is acquired, bythe in-vehicle reporting apparatus 1 wirelessly communicating with eachtransmission apparatus 2, and reporting that depends on the acquired airpressure is performed. The in-vehicle reporting apparatus 1 is anin-vehicle apparatus such as an ECU (Electronic Control Unit) disposedunderneath the driver's seat of the vehicle C, for example, andtransmits a request signal requesting air pressure information usingradio waves on the LF (Low Frequency) band to each transmissionapparatus 2. The transmission apparatus 2 detects the air pressure ofthe tire 3 mounted on the tire wheel to which the transmission apparatus2 is attached, in response to the request signal of the in-vehiclereporting apparatus 1, and transmits the detected air pressure and anapparatus ID which will be discussed later to the in-vehicle reportingapparatus 1 using radio waves on the UHF (Ultra High Frequency) band.Note that the LF band and the UHF band are examples of radio wave bandsthat are used when performing wireless communication, and the presentinvention is not necessarily limited thereto.

FIG. 2 is a block diagram showing the configuration of the transmissionapparatus 2. The transmission apparatus 2 includes a control unit 21.The control unit 21 includes a CPU 21 a that controls the operations ofeach constituent element. The CPU 21 a is constituted by one or aplurality of CPUs (Central Processing Units), a multi-core CPU, or thelike, for example. Also, a storage unit 21 b, a temporary storage unit21 c, an input-output I/F 21 d and a communication I/F 21 e areconnected to the CPU 21 a via a bus. The CPU 21 a reads out a controlprogram, which will be discussed later, stored in the storage unit 21 b,and controls each element. Here, the transmission apparatus 2 includes abattery which is not illustrated, and operates using power from thebattery.

The storage unit 21 b is a nonvolatile memory such as an EEPROM(Electrically Erasable Programmable ROM) or a flash memory. The controlprogram for the CPU 21 a to perform processing is stored in the storageunit 21 b. The control program is a computer program in which processingcontents for when the transmission apparatus 2 communicates with thein-vehicle reporting apparatus 1 and processing contents for whencontrolling each element are described. Also, an apparatus IDidentifying the transmission apparatus 2 is stored in the storage unit21 b. Here, the transmission apparatus 2 of the present embodiment isuniquely provided on each tire 3, and the apparatus ID is informationalso identifying the tire 3.

The temporary storage unit 21 c is a memory such as an SRAM (Static RAM)or a DRAM (Dynamic RAM). The temporary storage unit 21 c temporarilystores various types of data that are produced as a result of the CPU 21a performing processing according to the control program.

A pressure sensor 22 is connected to the input-output I/F 21 d. Thepressure sensor 22 includes a diaphragm, for example, and detects anabsolute pressure (air pressure) of the tire 3, based on the amount ofdeformation of the diaphragm, which changes depending on the magnitudeof pressure. Absolute pressure is the magnitude of pressure that isreferenced on an absolute vacuum. Note that although, in the presentembodiment, air pressure that is detected by the pressure sensor 22 isdescribed as being the absolute pressure, a configuration that detects agauge pressure or a difference pressure indicating the magnitude ofpressure relative to a predetermined reference pressure may also beadopted. The predetermined reference pressure is a median value, a lowerlimit or an upper limit of a range of air pressures in a state where thestate of the tire 3 does not need to be inspected, for example.

The pressure sensor 22 outputs the detected air pressure of the tire 3to the CPU 21 a via the input-output I/F 21 d. The CPU 21 a generates asignal including the air pressure of the tire 3 and the apparatus IDthat is stored in the storage unit 21 b, by executing the controlprogram.

A transmission unit 23 to which an RF transmitting antenna 25 isconnected, and a reception unit 24 to which an LF receiving antenna 26is connected are connected to the communication I/F 21 e. Thetransmission unit 23 modulates the signal generated by the CPU 21 a to asignal of a frequency band on the UHF band, and transmits the modulatedsignal from the RF transmitting antenna 25. The reception unit 24receives a request signal transmitted from the in-vehicle reportingapparatus 1 using radio waves of the LF band via the LF receivingantenna 26, and outputs the received signal to the CPU 21 a.

FIG. 3 is a block diagram showing the configuration of the in-vehiclereporting apparatus 1. The in-vehicle reporting apparatus 1 includes acontrol unit 11, and the control unit 11 includes a CPU 11 a thatcontrols the operations of each constituent element. The CPU 11 a isconstituted by one or a plurality of CPUs, a multi-core CPU or the like,for example. Also, a storage unit 11 b, a temporary storage unit 11 c, acommunication I/F 11 d, a clocking unit 11 e and an input-output I/F 11f are connected to the CPU 11 a via a bus. The CPU 11 a reads out thecontrol program, which will be discussed later, stored in the storageunit 11 b, and controls each element.

The storage unit 11 b is a nonvolatile memory that enables informationto be rewritten, such as an EEPROM or a flash memory. The controlprogram for the CPU 11 a to perform processing is stored in the storageunit 11 b. The control program is a computer program in which processingcontents for generating a request signal or the like when communicatingwith the plurality of transmission apparatuses 2 and processing contentsfor when controlling each element is stored. Also, a correspondencetable 12 is stored in the storage unit 11 b. The correspondence table 12is a table in which the correspondence relationship between the mountingposition of each of the plurality of tires 3 and the apparatus ID of thetransmission apparatus 2 disposed on each tire 3 is stored, and will bediscussed later.

The temporary storage unit 11 c is a memory such as an SRAM or a DRAM.The storage unit 11 c temporarily stores various types of data that areproduced as a result of the CPU 11 a performs processing according tothe control program.

A transmission unit 13 to which an LF transmitting antenna 18 isconnected and a reception unit 14 to which an RF receiving antenna 19 isconnected are connected to the communication I/F 11 d. The transmissionunit 13 modulates a request signal generated by the CPU 11 a to a signalof a frequency band on the LF band or the like, and transmits themodulated signal from the LF transmitting antenna 18. The reception unit14 receives a signal transmitted using radio waves of the UHF band fromeach of the plurality of transmission apparatuses 2 via the RF receivingantenna 19, and outputs the received signals to the CPU 11 a. Note thatone LF transmitting antenna 18 may be provided in the in-vehiclereporting apparatus 1, or a plurality of LF transmitting antennas 18 maybe provided in positions approximating the tires 3.

The clocking unit 11 e is constituted by a timer, a real-time clock orthe like, for example, and starts clocking in accordance with thecontrol of the CPU 11 a and provides a clocking result to the CPU 11 a.

A reporting unit 15, a vehicle height sensor 16 and a vehicle speedsensor 17 are connected to the input-output I/F 11 f. The reporting unit15 is, for example, a warning light provided on an instrument panel infront of the driver's seat, a display screen of car navigation, anin-vehicle speaker or the like, and reports information related to theair pressure of the plurality of tires 3. The CPU 11 a switches thereporting mode of the reporting unit 15, based on information, whichwill be discussed later, acquired from the vehicle height sensor 16. Thereporting mode of the reporting unit 15 will be discussed in detaillater.

The vehicle height sensor 16 is, for example, provided in the suspensionof each tire wheel of the vehicle C, and outputs a voltage that dependson the amount of elasticity of the suspension to the CPU 11 a. Thevehicle height sensor 16 is used in control related to optical axisadjustment of headlights provided in the vehicle C, and is used inpressure control in the case where the suspension is air suspension. TheCPU 11 a detects the vehicle height of the vehicle C, based on thevoltage. At this time, the CPU 11 a functions as a vehicle heightacquisition unit, by executing the control program. Note that thevehicle height sensor 16 need only be configured to output informationrelated to the vehicle height of the vehicle C to the CPU 11 a, and maybe configured to directly detect the vehicle height of the vehicle C andoutput information on the detected vehicle height to the CPU 11 a, or tooutput information related to vehicle height other than the amount ofelasticity of the suspension to the CPU 11 a.

The speed sensor 17 is, for example, provided on the axle of the vehicleC, and outputs a pulse signal that depends on the rotation of the axleto the CPU 11 a. The CPU 11 a detects the vehicle speed of the vehicle Cbased on the pulse signal. Note that any configuration that enables thespeed sensor 17 to output information related to vehicle speed such asthe speed of the vehicle C or the speed of the wheels to the CPU 11 amay be used.

FIG. 4 is an explanatory diagram showing a specific example of thecorrespondence table 12. The correspondence table 12 stores, for everyapparatus ID, the mounting position of the tire 3 that is identified bythe apparatus ID. For example, in the correspondence table 12 in FIG. 4,the tire 3 that is identified by the apparatus ID 1 is provided on thefront right of the vehicle C. Similarly, the tire 3 that is identifiedby the apparatus ID 2 is provided on the back right of the vehicle C,the tire 3 that is identified by the apparatus ID 3 is provided on thefront left of the vehicle C, and the tire 3 that is identified by theapparatus ID 4 is provided on the back left of the vehicle C. Note that,with the correspondence table 12, as long as the apparatus IDs and themounting positions of the tires 3 identified by the apparatus IDs can bestored in the storage unit 11 b in association with each other, the datastructure at the time of storage is not limited.

The in-vehicle reporting apparatus 1, for example, updates thecorrespondence table 12 in the case where the vehicle C has startedrunning, after determining that one or more of the tires 3 has beenreplaced. The in-vehicle reporting apparatus 1, for example, updates thecorrespondence table 12 based on the phase difference of the tire wheelsof the vehicle C at a predetermined time interval, the reception signalstrength of radio waves on the UHF band transmitted from thetransmission apparatuses 2, or the like. Here, an example in which thecorrespondence table 12 is updated based on the phase difference of thetire wheels will now be shown. Note that updating of the correspondencetable 12 may be performed other than as shown in the example below.

The in-vehicle reporting apparatus 1 detects information related to therotation angle of each tire wheel of the vehicle C with a sensor or thelike that is used in an ABS (Antilock Brake System), and calculates thephase difference of each tire wheel in a predetermined time interval,based on the detected information. Also, each transmission apparatus 2detects information related to the rotation angle of the tire wheel onwhich the transmission apparatus 2 is disposed with a rotation sensor,an acceleration sensor or the like, calculates the phase difference ofthe tire wheel in a predetermined time interval, based on the detectedinformation, and transmits the phase difference to the in-vehiclereporting apparatus 1. The in-vehicle reporting apparatus 1 compares thephase differences transmitted from the transmission apparatuses 2 withthe phase difference calculated by the in-vehicle reporting apparatus 1,and stores the tire wheel mounting position corresponding to the phasedifference having the highest correlation and the apparatus ID of thattransmission apparatus 2 in the correspondence table 12 in associationwith each other. The in-vehicle reporting apparatus 1 updates thecorrespondence table 12 by comparing the phase differences for therespective transmission apparatuses 2, and storing the correspondingmounting positions and the apparatus IDs in the correspondence table 12.

Here, in the case where the mounting positions of two tires 3 areinterchanged, the correspondence relationship between the mountingpositions of the tires 3 and the transmission apparatuses 2 stored inthe correspondence table 12 differs from the actual correspondencerelationship, until the correspondence table 12 is updated.

In the reporting system constituted as described above, the in-vehiclereporting apparatus 1 determines whether any of the tires 3 have beenreplaced, based on the vehicle height acquired using the vehicle heightsensor 16, and switches the reporting mode of information related to theair pressure of the tires 3 by the reporting unit 15 according to thedetermination result. A specific example of the reporting mode by thereporting unit 15 when the in-vehicle reporting apparatus 1 determinesthat none of the tires 3 have been replaced, and a specific example ofthe reporting mode by the reporting unit 15 when the in-vehiclereporting apparatus 1 determines that one or more of the tires 3 havebeen replaced will now be shown.

FIGS. 5A and 5B are diagrams showing specific examples of the reportingmode by the reporting unit 15. FIGS. 5A and 5B are enlarged views of thereporting unit 15 provided on the instrument panel, and the reportingunit 15 is provided with a display unit shaped like the vehicle C andvisually displays information related to air pressure around the displayunit. FIG. 5A shows an example of the reporting mode of the reportingunit 15 when the in-vehicle reporting apparatus 1 determines that noneof the tires 3 have been replaced. In the reporting mode, the value ofthe air pressure of each tire 3 is displayed around the display unit,and the display position of each value corresponds to the mountingposition of each tire 3. Specifically, the display “32” in FIG. 5Aindicates the value of the air pressure of the tire 3 provided on thefront right of the vehicle C, and, the display “28” indicates the valueof the air pressure of the tire 3 provided on the front left of thevehicle C. Similarly, the display “24” in FIG. 5A indicates the value ofthe air pressure of the tire 3 provided on the back right of the vehicleC, and the display “26” indicates the air pressure of the tire 3provided on the back left of the vehicle C.

FIG. 5B shows an example of the reporting mode of the reporting unit 15in the case where the in-vehicle reporting apparatus 1 determines thatone or more of the tires 3 have been replaced. In the case where evenone of the air pressures respectively transmitted from the transmissionapparatuses 2 is low, necessitating inspection, replacement or the likeof the tire 3, the in-vehicle reporting apparatus 1 displays a warningmessage such as “Tire Pressure Low” and reports that that the airpressure of one of the tires 3 is low. At this time, the in-vehiclereporting apparatus 1 performs reporting with the reporting unit 15without identifying the tire 3 whose air pressure is low.

Note that a configuration may be adopted in which, in FIG. 5A, in thecase where the air pressure of one or a plurality of tires 3 is low, thetire 3 whose air pressure is low is identifiably reported, by displayingthe value of the air pressure of the target tire 3 in a highlightedmanner and displaying a warning message such as shown in FIG. 5B.

Errors in reporting can be prevented even in a period during which thecorrespondence table 12 has not been updated after any of the tires 3have been replaced, by the in-vehicle reporting apparatus 1 switchingthe reporting mode of information related to air pressure as describedabove.

Next, processing performed by the in-vehicle reporting apparatus 1 fordetermining whether any of the tires 3 have been replaced and forswitching the reporting mode of information related to air pressure willbe described.

FIG. 6 is a flowchart showing a processing procedure performed by thein-vehicle reporting apparatus 1 when determining whether a tire 3 hasbeen replaced based on the vehicle height of the vehicle C. The CPU 11 aof the control unit 11 in the in-vehicle reporting apparatus 1determines whether a sampling timing at which to acquire the vehicleheight of the vehicle C has been reached (step S11). The CPU 11 a, forexample, determines that the sampling timing at which to acquire thevehicle height has been reached, whenever a predetermined time periodelapses in a state where the vehicle C has stopped. The CPU 11 adetermines whether the vehicle C has stopped using the vehicle speedsensor 17, for example. Also, the predetermined time period is 5seconds, for example.

If it is determined that the sampling timing at which to acquire thevehicle height of the vehicle C has not been reached (S11: NO), the CPU11 a holds processing until the sampling timing is reached. On the otherhand, in the case where it is determined that the sampling timing atwhich to acquire the vehicle height of the vehicle C has been reached(S11: YES), the CPU 11 a acquires the vehicle height of the vehicle Cfrom a voltage input from the vehicle height sensor 16 or the like (stepS12).

The CPU 11 a, having acquired the vehicle height, determines whether theacquired vehicle height is greater than or equal to a predeterminedheight (step S13). The predetermined height is set lower than thevehicle height when the vehicle C has been lifted up when replacing anyof the tires 3, and higher than the vehicle height when the vehicle Cbounces up while traveling or the like. If the acquired vehicle heightis not greater than or equal to the predetermined height, that is, islower than the predetermined height (S13: NO), the CPU 11 a resets theclocking of the clocking unit 11 e (step S14). The CPU 11 a outputs areset signal related to resetting of the clocking to the clocking unit11 e. Thereafter, the CPU 11 a returns the processing to step S11.

If it is determined that the acquired vehicle height is greater than orequal to the predetermined height (S13: YES), the CPU 11 a determineswhether the clocking unit 11 e is currently clocking (step S15). If itis determined that the clocking unit 11 e is not currently clocking(S15: NO), the CPU 11 a causes the clocking unit 11 e to start clocking(step S16), and thereafter returns the processing to step S11.

If it is determined that the clocking unit 11 e is currently clocking(S15: YES), the CPU 11 a determines whether a predetermined time periodhas elapsed from when the clocking unit 11 e started clocking (stepS17). The predetermined time period is the time period required toreplace at least one tire 3, and, as one example, is 5 minutes. The CPU11 a functions as a vehicle height determination unit, by executing thecontrol program in steps S13 to S17.

If it is determined that the predetermined time period has not elapsed(S17: NO), the CPU 11 a returns the processing to step S11. On the otherhand, if it is determined that the predetermined time period has elapsed(S17: YES), the CPU 11 a resets the correspondence table 12 (step S18).Specifically, the CPU 11 a erases the contents of the correspondencetable 12. The processing of step S18 indicates that the CPU 11 a hasdetermined that one or more of the tires 3 have been replaced.Thereafter, the CPU 11 a ends the processing.

FIG. 7 is a flowchart showing a processing procedure performed by thein-vehicle reporting apparatus 1 when reporting information related tothe air pressure of a tire 3. The CPU 11 a of the control unit 11 in thein-vehicle reporting apparatus 1 determines whether the transmissiontiming of the request signal has arrived (step S21). The CPU 11 adetermines that the transmission timing of the request signal hasarrived, whenever a predetermined time period elapses in a state wherethe drive source of the vehicle C has started, for example. Thepredetermined time is 1 second, for example.

If it is determined that the transmission timing has not arrived (S21:NO), the CPU 11 a stands by until the transmission timing arrives. Onthe other hand, if it is determined that the transmission timing hasarrived (S21: YES), the CPU 11 a sequentially transmits the requestsignal to each transmission apparatus 2 (step S22).

Each transmission apparatus 2, having received the request signal,detect the air pressure of the tire 3 mounted on the tire wheel on whichthe transmission apparatus 2 is disposed as described above, andtransmits the detected air pressure and the apparatus ID of thetransmission apparatus 2 to the in-vehicle reporting apparatus 1.

The CPU 11 a determines whether an air pressure and an apparatus IDtransmitted from a transmission apparatus 2 in response to thetransmitted request signal have been received (step S23). If it isdetermined that an air pressure and an apparatus ID have not beenreceived (S23: NO), the CPU 11 a stands by until an air pressure and anapparatus ID are received. The reception unit 14 that receives the airpressure and the apparatus ID in step S23 corresponds to an air pressureinformation acquisition unit.

If it is determined that an air pressure and an apparatus ID have beenreceived (S23: YES), the CPU 11 a determines whether any of the tires 3of the vehicle C have been replaced (step S24). Specifically, the CPU 11a determines whether any of the tires 3 have been replaced, depending onwhether contents are stored in the correspondence table 12.

If it is determined that one or more of the tires 3 have been replaced(S24: YES), the CPU 11 a determines whether the received air pressure isless than or equal to a predetermined threshold (step S25). Thepredetermined threshold is a value at which replacement, inspection orthe like of a tire 3 is required in order to prevent problems fromoccurring due to a decrease in the air pressure of the tire 3 when thevehicle C is running. The CPU 11 a functions as an air pressurethreshold determination unit by executing the control program in stepS25. If it is determined that the received air pressure is not less thanor equal to the predetermined threshold, that is, that the air pressureis higher than the predetermined threshold (S25: NO), the CPU 11 a endsthe processing.

If it is determined that the received air pressure is less than or equalto the predetermined threshold (S25: YES), the CPU 11 a causes thereporting unit 15 to report a warning (step S26). The reporting unit 15reports in the above-mentioned mode shown in FIG. 5B. Thereafter, theCPU 11 a ends the processing.

On the other hand, if it is determined in step S24 that none of thetires 3 have been replaced (S24: NO), the CPU 11 a specifies themounting position of the tire 3 that is identified by the receivedapparatus ID (step S27). Specifically, the CPU 11 a specifies themounting position corresponding to the received apparatus ID, based onthe correspondence table 12 stored in the storage unit 11 b.

Next, the CPU 11 a determines whether the received air pressure is lessthan or equal to a predetermined threshold (step S28). The predeterminedthreshold is the same as the threshold used in the determination at stepS25. If it is determined that the received air pressure less than orequal to the predetermined threshold (S28: YES), the CPU 11 a causes thereporting unit 15 to report a warning indicating the value of thereceived air pressure and that the air pressure of that tire 3 is low,so that the specified tire 3 is identifiable (step S29). Thereafter, theCPU 11 a ends the processing.

On the other hand, if it determined that the received air pressure ishigher than the predetermined threshold (S28: NO), the CPU 11 a causesthe reporting unit 15 to report the received air pressure, so that thespecified tire 3 is identifiable (step S30). The reporting unit 15performs reporting in the above-mentioned mode shown in FIG. 5A.Thereafter, the CPU 11 a ends the processing.

Note that the processing procedure from steps S24 to S30 is a processingprocedure that the in-vehicle reporting apparatus 1 performs based onthe air pressure and the apparatus ID transmitted from one transmissionapparatus 2. The in-vehicle reporting apparatus 1 performs thisprocessing procedure every time an air pressure and an apparatus ID arereceived from a transmission apparatus 2.

As a result of the above configuration and processing, the in-vehiclereporting apparatus 1 is able to determine whether the tires 3 have beenreplaced based on the acquired vehicle height of the vehicle C, and isable to change the reporting mode depending on whether any of theplurality of tires 3 provided on the vehicle C have been replaced. Thein-vehicle reporting apparatus 1 of the present embodiment reportsinformation that depends on the mounting position of a tire 3 and theair pressure of that tire 3, in the case where none of the tires 3 havebeen replaced, and does not perform reporting for every mountingposition, in the case where any of the tires 3 have been replaced. Thus,errors in reporting can be prevented, by not performing reporting of thecorrespondence relationship of the mounting positions of the tires 3 andthe transmission apparatuses 2 that is based on the correspondence table12, in the period until the correspondence table 12 is updated. Also,the in-vehicle reporting apparatus 1 is able to use a configurationcapable of detecting vehicle height that can be installed in a typicalvehicle such as the vehicle height sensor 16 that is used in controlrelated to optical axis adjustment of headlights, pressure control ofair suspension or the like, and to suppress an increase in costsconcerning the configuration.

Also, the in-vehicle reporting apparatus 1 is able to prevent errors inreporting in the case where any of the plurality of tires 3 have beenreplaced, by not reporting, for every mounting position of a tire 3,information that depends on the air pressure of the tire 3, for example.Also, the user can at least be made aware that the air pressure of oneor more of the tires 3 is low even in the case where a tire 3 of thevehicle C has been replaced. Thus, convenience for the user can beimproved.

Also, the in-vehicle reporting apparatus 1 is able to very accuratelydetermine whether replacement of a tire 3 has been performed, bydetermining that a tire 3 has been replaced, in the case where theheight of the vehicle is continuously greater than or equal to apredetermined height.

Note that although the present embodiment describes the reporting unit15 as reporting information that depends on the air pressures receivedfrom the transmission apparatuses 2 using the reporting modes shown inFIGS. 5A and 5B, other reporting modes may be adopted. That is, thereporting unit 15 may report using display, sound, vibration or thelike, as long as information that depends on the mounting positions andthe air pressures of the tires 3 is reported, in the case where a tire 3has not been replaced. Similarly, the reporting unit 15 may report usingdisplay, sound, vibration or the like, as long as information thatdepends on the mounting positions of the tires 3 is not reported, in thecase where a tire 3 has been replaced. For example, the reporting unit15 may be configured to display only the minimum value among the airpressures transmitted from the transmission apparatuses 2 or to displaythe plurality of air pressures in enumerated form, in the case where atire 3 has been replaced.

Also, although the present embodiment describes the transmissionapparatuses 2 as transmitting the air pressures of the tires 3 inresponse to a request from the in-vehicle reporting apparatus 1, aconfiguration may be adopted in which the transmission apparatuses 2transmit the air pressures of the tires 3 at a predetermined timing. Thepredetermined timing is whenever a predetermined time period such as 1second elapses after a predetermined point in time such as when thetires rotate or the engine starts, for example, and can be set asappropriate. At this time, the configuration of the transmission unit 13and the LF transmitting antenna 18 of the in-vehicle reporting apparatus1 and the reception unit 24 and the LF receiving antenna 26 of thetransmission apparatus 2 is not essential. Also, at this time, it is notessential for the in-vehicle reporting apparatus 1 to perform theprocessing of steps S21 and S22 in FIG. 7.

Also, although the present embodiment described an example in which thein-vehicle reporting apparatus 1 acquires the air pressure as a resultof receiving the air pressure detected and transmitted by thetransmission apparatus 2, a configuration may be adopted in which otherinformation related to air pressure is acquired. For example, aconfiguration may be adopted in which the transmission apparatus 2transmits the level of the air pressure such as “high”, “normal” or“low” according to the air pressure detected by the transmissionapparatus 2, and the in-vehicle reporting apparatus 1 receives andreports the level of the air pressure.

Also, although step S18 of FIG. 6 shows the CPU 11 a resetting thecorrespondence table 12, the fact that one or more of the tires 3 havebeen replaced may be indicated by processing other than resetting thecorrespondence table 12. For example, a configuration may be adopted inwhich the CPU 11 a performs processing for temporarily storinginformation indicating that one or more of the tires 3 has been replacedin the storage unit 11 c at step S18, and determines whether thisinformation is temporarily stored in the storage unit 11 c at step S24of FIG. 7. In other words, any processing may be performed in step S18,as long as the reporting mode of the reporting unit 15 can be switched,based on the vehicle height of the vehicle C being greater than or equalto a predetermined height.

Furthermore, although the in-vehicle reporting apparatus 1 determinesthat the air pressure of a corresponding tire 3 is low by determiningwhether the air pressure transmitted from the transmission apparatus 2is less than or equal to a predetermined threshold in steps S25 and S28of FIG. 7, other anomalies in air pressure may be determined. Thein-vehicle reporting apparatus 1 may, after determining that the airpressure is not less than or equal to the predetermined threshold instep S25 and step S28, determine whether the air pressure is greaterthan or equal to a second threshold that is larger than the firstthreshold, for example. In this case, the in-vehicle reporting apparatus1 is determining whether the air pressure is a high air pressurerequiring inspection, replacement or the like of the tire 3. Also, if itis determined that the air pressure is greater than or equal to thesecond threshold, the in-vehicle reporting apparatus 1 may be configuredto display a warning message such as “Tire Pressure High” on thereporting unit 15.

The invention claimed is:
 1. An in-vehicle reporting apparatus thatincludes an air pressure information acquisition unit configured toacquire identification information identifying each of a plurality oftires provided on a vehicle and air pressure information related to anair pressure of each of the plurality of tires, and that performsreporting that depends on the identification information and the airpressure information acquired by the air pressure informationacquisition unit, comprising: a storage unit configured to store amounting position of each of the plurality of tires in association withthe identification information identifying the tire; a vehicle heightacquisition unit configured to acquire a vehicle height of the vehicle;a vehicle height determination unit configured to determine whether thevehicle height acquired by the vehicle height acquisition unit isgreater than or equal to a predetermined height; an air pressurethreshold determination unit configured to determine whether an airpressure indicated by the acquired air pressure information is less thanor equal to a predetermined threshold; and a detection unit configuredto report information that depends on the mounting position of a tirestored in the storage unit in association with the identificationinformation acquired by the air pressure information acquisition unitand on the air pressure information of the tire acquired by the airpressure information acquisition unit, in a case where the vehicleheight determination unit determines that the acquired vehicle height isnot greater than or equal to the predetermined height, and to report aresult of the determination by the air pressure threshold determinationunit that depends on the air pressure information of the tire acquiredby the air pressure information acquisition unit, without reporting atleast information that depends on the mounting position of the tire, ina case where the vehicle height determination unit determines that theacquired vehicle height is greater than or equal to the predeterminedheight.
 2. The in-vehicle reporting apparatus according to claim 1,wherein the vehicle height acquisition unit is configured to acquire thevehicle height of the vehicle repetitively, and the vehicle heightdetermination unit is configured to determine whether the vehicle heightrepetitively acquired by the vehicle height acquisition unit iscontinuously greater than or equal to the predetermined height forgreater than or equal to a predetermined time period or a predeterminednumber of times.
 3. A reporting system comprising: the in-vehiclereporting apparatus according to claim 2; and a plurality oftransmission apparatuses respectively disposed on a plurality of tirewheels provided on a vehicle, and configured to detect an air pressureof a corresponding tire, and transmit air pressure information includingthe detected air pressure and identification information identifying thecorresponding tire, wherein the air pressure information acquisitionunit is configured to acquire the air pressure information and theidentification information transmitted from each of the plurality oftransmission apparatuses.
 4. A reporting system comprising: thein-vehicle reporting apparatus according to claim 1; and a plurality oftransmission apparatuses respectively disposed on a plurality of tirewheels provided on a vehicle, and configured to detect an air pressureof a corresponding tire, and transmit air pressure information includingthe detected air pressure and identification information identifying thecorresponding tire, wherein the air pressure information acquisitionunit is configured to acquire the air pressure information and theidentification information transmitted from each of the plurality oftransmission apparatuses.